It is often helpful to examine a character and test whether it is upper- or
lowercase, or whether it is a character or a digit. The string module
provides several constants that are useful for these purposes. One of these,
string.digits is equivalent to “0123456789”. It can be used to check if a character
is a digit using the in operator.

The string string.ascii_lowercase contains all of the ascii letters that the system
considers to be lowercase. Similarly, string.ascii_uppercase contains all of the
uppercase letters. string.punctuation comprises all the characters considered
to be punctuation. Run the following: